I don’t know particularly much about powershell, but a pipe | probably just redirects stdout to the following command, which appears to just store the output in a file, but does not print it on the terminal. That is the reason why the output is not visible on the terminal.
The remaining output is printed on stderr, which is not redirected with the command you’re currently using. So you’ll have to add some option to redirect stderr to stdout, maybe 2>&1 also works for Powershell, but I have no clue what the correct syntax is.
For hiding the powershell window, there are probably lots of tutorials available on the internet.